Preprints
https://doi.org/10.5194/angeo-2020-71
https://doi.org/10.5194/angeo-2020-71

  23 Oct 2020

23 Oct 2020

Review status: a revised version of this preprint was accepted for the journal ANGEO and is expected to appear here in due course.

Modelling the residual mean meridional circulation at different stages of stratospheric warming events

Andrey V. Koval1,2, Anna N. Bakhareva1, Ksenia A. Didenko1,2, Tatiana S. Ermakova1,2, Nikolai M. Gavrilov1, Alexander I. Pogoreltsev1,2, Olga N. Toptunova1,2, and Anton S. Zarubin1 Andrey V. Koval et al.
  • 1Atmospheric Physics Department, Saint-Petersburg State University, Saint-Petersburg, 198504, Russia
  • 2Department of Meteorological Forecasts, Russian State Hydrometeorological University, Saint-Petersburg, Russia

Abstract. Ensemble simulation of the general atmospheric circulation of the middle and upper atmosphere up to the lower thermosphere is performed using the 3-D nonlinear mechanistic numerical model MUAM. Residual mean meridional circulation (RMC) in terms of the Transformed Eulerian Mean is calculated for the boreal winter and changes in its vertical and meridional velocity components during different phases of simulated composite stratospheric warming (SW) events are studied. The simulation results show general decrease in RMC velocity components up to 30 % during and after SW in the mesosphere and lower thermosphere of the Northern Hemisphere. There are also increases in the downward and northward velocities at altitudes 50–70 km at the northern high latitudes. Associated changes in adiabatic heating/cooling rates can contribute to heating the stratosphere and cooling the mesosphere during the composite SW. The changes in the transport of conservative species (like ozone) during SWs are estimated. Weakening of ozone fluxes at the middle latitudes of the Northern Hemisphere may reach 30 % during SWs and 30–40 % after the events at the altitudes of stratospheric maximum of ozone concentration. Such statistically confident simulations of RMC reactions on SWs at altitudes up to the lower thermosphere are performed for the first time. The study of the residual meridional circulation is useful for effective analysis of wave impacts on the mean flow and for diagnostics of the transport of atmospheric gas species in the atmosphere.

Andrey V. Koval et al.

 
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Status: closed
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Andrey V. Koval et al.

Andrey V. Koval et al.

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Short summary
Numerical modeling is used to simulate atmospheric circulation and calculate residual mean meridional circulation (RMC) during sudden stratospheric warming event (SSW). Calculating the RMC is used to take into account wave effects on transport of atmospheric quantities and gas species in the meridional plane. The results show that RMC undergoes significant changes at different stages of SSW and also contribute to the SSW development.